Impact ram



Jan. 16, 1968 J. B. OTTESTAD IMPACT RAM 2 SheetsSheet 1 Filed Aug. 13,1965 M.\ w\ \N w NN N\ r QM mm 7 A, m mm M ii ww A Tram 5K5.

Jan. 16, 1968 J. B. OTTESTAD- IMPACT RAM 2 Sheets-Sheet 2 Filed Aug. 15,1965 INVENTOR. JACK 5. 0772557210 ATTORNEYS.

United States Patent 3,363,512 IMPACT RAM Jack B. Ottestad, La Jolla,Calif., assignor to Impulse Products Corporation, San Diego, Calif, acorporation of California Filed Aug. 13, 1965, Ser. No. 479,448 15Claims. (Cl. 915) ABSTRACT OF THE DHSCLOSURE This invention relates toan impact ram wherein a body has an internal plunger, which plunger isadapted to be axially driven relative to the body in order to deliver ablow. Means is provided for quickly impacting on the face of theplunger, energy which is stored in a chamber in preparation forrendering said blow.

This invention relates to fluid-powered impact rams.

Devices for striking bodies or surfaces are widely known. Theirobjective is to impart to the body or surface a quantity of energy in arelatively short time. The energy is usually derived from propelled orfreely falling weights, from powered linkages, from the quick release ofa fluid stored under pressure, or from an explosion. The field ofmechanisms powered by quick release of a fluid stored under pressure hasbeen the subject of much development, which development has beencharacterized by a steady increase in the complexity of the devices. Itis an object of this invention to provide an impact means which utilizesa minimum of parts which are easily and inexpensively manufactured andassembled.

It is another characteristic of conventional impact rams that theirenergy output is not readily adjustable so that blows of greater orlesser energy can be produced. This invention provides for readyselectivity from blow to blow of the energy level.

A very serious deficiency inherent in conventional fluidpowered deviceis the risk of misfire when attempting to unload them after the deviceis charged or cocked. Occasionally it is necessary, after charging themachine, to release the energy but without causing the machine toundergo a work-cycle. This has been difficult, and sometimes evenimpossible, to arrange for in previously-known machines, and thesemachines, when once charged, remain a potential danger to theiroperators until after a work stroke is completed, so that the energy isdischarged. The same problem arises when the enrgy of the charge is onlypartially discharged. This invention provides a safe, fluid-poweredimpact device which can always safely and quickly be unloaded withoutundergoing a work cycle.

Another serious problem in conventional devices occurs when the devicefires, but fails to strike a workpiece which would receive the energy.Then the traveling parts of the machine would continue in rapid motion,and serious damage to the machine is likely to result. The disadvantageand danger of such a situation i obvious, for were the machine tomisfire, or fire when for some reason there were no workpiece inposition (both of these being possibilities in routine factoryoperations), then serious damage is done to expensive capital equipment.This invention provides means which inherently decelerates therapidlymoving parts toward the end of a stroke, so that the device isfully protected against damage from this cause.

It is another object of this invention to provide a device which, whileuseful for impacting objects, can also provide a steady force to act asan arbor press, for example, or an oscillatory force to providevibrational energy.

An impact ram according to this invention includes a body having aninternal body cylinder extending along an axis of motion. The cylinderis closed at a first end of the Patented Jan. 16, 1968 ice body and openat a second end. A plunger is axially slidable in the body cylinder, andis adapted to be connected to an object, an example being an impact headfor use as a hammer, which object is disposed outside the body. Theplunger or means projects through the open second end of the bodycylinder.

The plunger has a lateral dimension which is less than a correspondinginternal lateral dimension of the body cylinder. The plunger carries acollar which makes a continuous peripheral fluid-sealing contact withthe inside wall of the body cylinder. A sliding seal disposed betweenthe plunger and the body forms one boundary of a variable volume returnchamber, the other boundaries of which are an inner wall of the body,the collar, the inner wall of the body cylinder, and the exteriorsurface of the plunger which has said lesser lateral dimension.

A return face is disposed on the collar which faces into the said returnchamber. Fluid pressure in the return chamber tends to return theplunger axially toward the first end of the body. A triggering surfaceon the collar faces the closed end of the cylinder.

A plunger cylinder extends axially in the plunger. A piston axi lyfloats in the plunger cylinder. The piston makes a fluid-sealing slidingfit with the inner wall of the plunger cylinder. The plunger cylinder isopen at its end facing the said first end of the body cylinder and isclosed at its other end. The piston forms an accumulator chamber ofvariable volume between itself and the closed end of the plungercylinder.

A peripheral charging seal includes a surface on the plunger that isdisposed laterally of the triggering surface, and a complementarysurface on the body inside the cylinder. When these surfaces mate toform a seal, there is an axial spacing which forms a triggering chamberbetween the triggering surface and the body. The triggering chamber,when the elements of the device are in such a position, is fullyenclosed. At this time, the piston faces the region of the body which isinside the seal. It faces this region through the open end of theplunger, and forms a charging chamber therein.

Respective port means is provided for admitting fluid under pressure tothe return chamber, the triggering chamber, the charging chamber, andthe accumulator chamber.

According to a feature of the invention, gas pressure is used todecelerate the moving portions of the device toward the end of thestroke.

According to a preferred but optional feature of the invention, thecylinders, the plunger, the piston and the seals are concentric aroundthe axis.

The above and other features of the invention will be fully understoodfrom the following detailed description and accompanying drawings inwhich:

FIG. 1 is a partial view in axial cross-section showing the presentlypreferred embodiment of the invention;

FIG. 2 is a cross-section taken at line 22 of FIG. 1;

FIGS. 36 are axial cross-sections showing the device of FIG. 1 insuccessive operative positions; and

FIG. 7 is a fragmentary drawing of optional triggering mean for thisinvention.

An impact ram 10 according to the invention has an axis 11 of motion inorder that oppositely directed forces may be exerted between two objectssuch as a frame, and an object or surface to be struck or pressed. Anexample of such an object is a pin to bev driven into or out of a hole.The ram includes a body 12 which encloses an axially-extending bodycylinder 13. At a first end 14, the cylinder is closed by an end cap 15that is threaded into the tubular portion 16 of the body. A peripheralsealing ring 17 seals between the tubular portion and the end cap.

At the second end of the body, there is an inwardly projecting collar 18(FIG. 6) which includes a seal 19 and a counterbore 19a for purposes yetto be described. The second end of the body is open so as to receive andmake a fluid sliding fit with a plunger 26 that is fitted into the bodycylinder.

A peripheral collar 21 is formed on the plunger, and it projectslaterally from a generally cylindrical side wail 22. It will now be seenthat a return chamber 23 of variable volume is formed between collars 1Sand 21, cylinder 13 and sidewall 22. Sidewall 22 has a. lesser lateral(radial) dimension than the wall of cylinder 13. Return surface 24 isformed on collar 21 and presents a net lateral area to pressure in thereturn chamber.

A seat insert 25 is threaded to the plunger so as to form a partthereof. The insert includes an opening 25a from an inside plungercylinder 26 to the end of the plunger adjacent to the first end of thebody cylinder.

At the end of the plunger which is adjacent to said first end, there isa peripheral surface 27 that is intended to mate with a like surface 28on the end cap. The region of collar 21 which lies radially outside ofthese surfaces when they are joined, and which faces toward the end cap,constitutes a triggering surface 29. The region between triggeringsurface 29 and the end cap, which lies radially outside of surfaces 27and 28 when they are joined, is denoted as a triggering chamber 30.

A piston 31 is slidably fitted in plunger cylinder 26. A sealing ring 32makes a fluid-sealing fit between the piston and the plunger cylinder. Astop shoulder 33 (FIG. 6) is formed in the plunger cylinder to limit themovement of the piston to the left in FIG. 3.

Insert 25 includes a tapered surface 35 which tapers inwardly towardopening 250, which it intersects. A nose 36 on the piston includes ametering pin 36a which is tapered, a cylindrical surface 36b whichenters opening 25a, leaving a clearance 36c, and a taper 36d with asmaller conical angle than that of surface 35. The metering pin and theclearance decelerate the piston near the end of its stroke, and enablefluid readily to reach the full right-hand face of the piston when thecharging operation is started.

The region between the central portion 37 of the end cap and the piston,within the plunger cylinder, is denoted as a charging chamber 38. Theregion within the plunger cylinder between its closed end and the pistonis denoted as an accumulator chamber 39.

The piston carries a seat intended to form a substantially fluid-tightseal with surface (seat) 35 on insert 25 when the nose is fully to theright as illustrated in FIG. 6. As soon as the piston moves slightly tothe left as in FIG. 1, spacing 48 between surfaces 35 and 45 becomespart of the charging chamber.

A residual charge of gas is injected into accumulator chamber 39 from asource 50 (see FIG. 3) through a valve 49. Valve 49 may simply be aplug, if desired, or any standard type of pressure retentive fillingvalve. Once this residual charge is injected, it is left in theaccumulator chamber, and this chamber requires no further attentionexcept for replacing gas which may leak out.

A triggering charge port 56 (FIGS. 1 and 3) passes through the end capand enters the triggering chamber. It receives triggering pressure froma source 57 through a valve 58. Valve 58 has two settings. In oneposition it vents port 56 to reservoir 59, and in the other connects itto pressure.

A return port 60 opens into the return chamber. It is adaptedselectively to be connected to a source of gas under pressure 61 such asbottle gas or a compressor or to vent 62. by a valve 63.

A charge port 65 opens into the charging chamber. A valve 66 is adaptedto connect or disconnect this port from a source 67 of fluid underpressure. Valve 66 is adapted to vent charging chamber 38 through line68.

Sources 57 and 67 provide liquid, although they could provide gas.Sources 50 and 61 provides a compressible gas such as compressednitrogen or helium.

The operation of the device as an impact ram is as follows.

Initially the accumulator chamber will be charged with its residualcharge. The pressure selected is one of the determinants of the energyoutput of the impact ram. In one device wherein the diameter of theplunger cylinder is about 3 inches, nitrogen gas, or some other inertgas is injected into the accumulator chamber to a pressure of about 1000p.s.i.g. to 1500 p.s.i.g. At this time all other regions in the deviceare vented to atmosphere. Then valve 49 is closed. As a result of thisresidual charge, the piston will be moved relative to the plunger justpast the location shown in FIG. 1, and the piston will be firmly seatedagainst surface 35. A fluid tight seal is not essential, although it isdesirable. The same is true of the other seals in these devices, becauseminor leakage therein does not impede the function of the device, norrender it subject to misfires.

At this time, the position of the plunger in the body is indefinite.Next, valve 58 is set so as to vent triggering port 56. Valve 63 is setto apply pressure in return chamber 23. This pressure, acting againstthe return face, and with the other side of collar 21 vented, moves theplunger fully to the right, to the position shown in FIG. 1. Pressure isbuilt up to the desired level, and valve 36 closed, thereby to trap agas charge in the return chamber. Alternatively, the valve may be leftopen, maintaining the return chamber at the pressure of source 61. Atthese conditions, surfaces 27 and 28 meet and seal, and triggeringchamber 30 is fully isolated from the rest of the systern. This plungercondition is shown in FIG. 1.

Next, pressure is applied to charging port 65 through valve 66, andbegins to overcome the resistance of the charge in the accumulatorchamber, and moves the piston to the left. This is the start of thecharging operation which is shown partially completed in FIG. 3. In FIG.3 the device is shown charged, but to less than its maximum energy. Theplunger is locked in the position of FIGS. 1 and 3, because of thedifferent forces on the return and triggering surfaces, the force on thereturn surface being the greater. The residual charge in accumulatorchamber 39 is compressed as the piston moves to the left, the amount ofcompression being proportional to the pressure exerted in chargingchamber 38. There therefore exists a discrete axial position of thepiston in the plunger for each pressure level within a wide range, andthe energy level can be set by adjusting the charging pressure.

If the charging pressure is great enough, the piston will be movedagainst stop 33, and there will be no further compression of theaccumulator charge. In the example given, a charge pressure of 2500p.s.i.g. is often used to fully charge the device. Energy is now storedin the accumulator chamber, and the plunger is locked onto the body bydiiferential force across collar 21.

At this time it is perfectly safe to vent charging chamber 38 to line68, and the energy will harnilessly be dissipated and the devicesafetied, should a work stroke not be desired. The piston would simplyreturn to its initial position at the open end of the plunger. This is avery important safety advantage over prior art devices.

Assuming the charge is to be used for impact purposes, the ram may betriggered by setting valve 58 to apply pressure to triggering port 56and thereby triggering chamber 30. The force in the triggering chamberwill overcome the force maintaining the seal at surfaces 27 separate theseals, and then the triggering chambers will quickly receive theirpressure and complete the triggering operation. In this regard, thehigher pressure may be considered triggering means.

The movement of the plunger to the left is caused by movement of thepiston to the right (relative to the plunger), thereby exerting theenergy of the accumulator charge on the liquid in the charging chamber.The plunger expels liquid from the plunger cylinder into the bodycylinder as it moves.

Preferably, the piston will approach the end of its stroke and havetransferred the maximum energy to the plunger, by the time the plungerhas traveled between about /3 and h of its maximum length of stroke. Thedevice is shown at this condition in FIG. 5. It is preferable for impactto occur at the point shown in FIG. 5 and the impact would dissipate theenergy.

However, now assume that nothing is struck by a body such as hammer 100,or that the blow is not totally absorbed. Then the plunger mustdecelerate, or the device will be damaged. The remained of the strokeaccomplishes that deceleration. This deceleration is accomplished bycompression of gas in return chamber 23. Finally, the end of the strokeis reached as shown in FIG. 6 and recycling can be done. The pressure inthe return chamber tends to return the plunger toward the first end ofthe cylinder. An undesirable slam-back is prevented by the cushioningeffect of the piston and the gas in the accumulator.

Counterbore 19a provides a residual chamber for return fluid, and alsokeeps port 60 from being blocked by the plunger.

To repeat the cycle, the plunger will be returned to seal at surfaces 27and 28 by pressure in return chamber 23 with valve 66 set so as to ventport 65. With valve 58 again set to vent, application of pressure to thecharging chamber will compress the charge in accumulator chamber 39 toready the machine for another stroke. Applying pressure to triggeringchamber 30 again initiates the stroke.

Attention is called to the fact that seals 27 and 28 are cylindrical.They need not be, but it has been found that when the device is beingcycled rapidly, for example once per second, that if laterally-extendingseals are used, they may bounce, and the device chatters and slows down.There can be no bounce between concentric cylindrical seals. Slightleakage between these seals is of no consequence, because the triggeringchamber is vented except when triggering is desired.

The triggering circuitry is optional. Instead of a fluid pressure, atriggering pin 102 (FIG. 7) could be provided through the end capmechanically to force the plunger oh its seal with the body to initiatethe cycle.

Triggering chamber 30 is not placed under pressure to trigger the devicein the embodiment of FIG. 12 as it is in the embodiment of FIG. 1. InFIG. 12 a mechanical force to move the plunger away from end cap 15 isexerted directly on the plunger by pin 102. However, in bothembodiments, chamber 30 must be provided in order for the plunger to beretained in the charged condition until it is fired, and the termtriggering is used in both embodiments as a matter of convenience anduniformity in description even though the chamber itself is not used forthe provision of a fluid triggering force in the embodiment of FIG. 12.

The peripheral seals, cylinders and chambers are all preferably coaxialand round. The relative motions are all axial, along axis 11.

Any suitable gas may be used where gas is called for, but preferably thegas used should be inert and inexpensive. Nitrogen is the preferred gas.Any good hydraulic fluid which will not break down under the rapid flowconditions involved herein may be used where working liquid is calledfor.

The device can also be used as a standard press, by

venting the return chamber to reservoir and applying pressure throughthe triggering port, or simply by applying pressure to the triggeringport and compressing the gas in return chamber 23 by overpowering itwith a greater force. Return motion is accomplished by reversing theseconnections or venting the charging or triggering port.

The invention provides a versatile imapct ram which can be made in awide range of sizes, each of said sizes being operable over a wide rangeof residual accumulator charges and charge levels in charging chamber38, which is fail safe, includes effective deceleration means, and canbe used as a standard press and as a vibrating device. Its simplicity isevident from the drawings. It requires only a bare minimum of parts, allof simple configuration, with only a bare minimum of criticaldimensions.

It is to be noted that the accumulator charge need not be fullycompressed to operate the device. With less compression, less energywill be imparted per blow.

This invention is not to be limited by the embodiments shown in thedrawings and described in the description, which are given .by way ofexample and not of limitation, but only in accordance with the scope ofthe appended claims.

I claim:

1. An impact ram having an axis, comprising: a body having an internal,axially-extending body cylinder; 21 plunger having an internal,axially-extending plunger cylinder; a piston axially slidably fitted insaid plunger cylinder, the body and plunger, and the piston and plungerbeing relatively axially slidable; a laterally-extending collar on thebody making a substantially fluid-sealing fit with the external surfaceof the plunger; a laterallyextending collar on the plunger making asubstantially fluid-sealing fit with the body cylinder, whereby a returnchamber of variable volume is defined by the body cylinder, the plungerand the collars, the return chamber being adapted to receive gas underpressure; a return surface on the plunger collar facing into the returnchamber; a triggering surface on the plunger collar facing toward afirst, closed end of the body within the body cylinder; a peripheralseal carried by the body at said first end thereof inside the bodycylinder; a peripheral seal carried by the plunger at its end adjacentsaid seal on the body, the plunger cylinder having an openingcommunicating with said last-named seal, whereby the said two seals areadapted to make a fluid-sealing closure when the plunger is moved to itsfull extent toward said first end, said closure separating a triggeringchamber formed between the said first end and the triggering surfacewithin the body cylinder from a charging chamber formed between saidfirst end and the piston inside the plunger cylinder, the opposite endof the plunger cylinder being closed, whereby the piston forms anaccumulator chamber of variable volume, said accumulator and chargingchambers being separated from each other by the piston; an accumulatorport opening into the accumulator chamber for admitting gas underpressure thereinto; means movable with the piston for containing the gasin the accumulator chamber; conduitry opening into the body in fluidcommunication with the charging chamber; valve means controlling flow offluid in said conduitry; and triggering means for moving the plungeraway from said first end; whereby fluid under pressure in the returnchamber moves the plunger to said full extent to cause said seals toseat, and then fluid from the conduitry enters the charging chamber tomove the piston against gas in the accumulator chamber, and thereafterthe triggering means is actuable to move the plunger so as to separatethe seals and exert pressure of the charging chamber over the fulllateral area of the plunger, and the plunger body moves axially so as toincrease the spacing between the first end of the body and thetriggering surface under force derived from pressure in the chargingchamber.

2. An impact ram according to claim 1 in which the opening in theplunger adjacent said first end is tapered, narrowing toward said firstend, and in which the piston includes a reduced portion adapted to entersaid opening so as gradually to reduce the lateral separation betweenthem, thus decelerating the plungers motion away from the first end.

3. An impact ram according to claim 1 in which a stop shoulder is formedin the plunger cylinder, spaced from the open end for limiting thetravel of the piston away from said first end.

4. An impact ram according to claim 3 in which the opening in theplunger adjacent said first end is tapered, narrowing toward said firstend, and in which the piston includes a reduced portion adapted to entersaid opening so as gradually to reduce the lateral separation betweenthem, thus decelerating the plungers motion away from the first end.

5. An impact ram according to claim 1 in which the triggering meanscomprises a mechanical element adapted to force the plunger away fromsaid first end.

6. An impact ram according to claim 1 in which the triggering meanscomprises a triggering port opening into the triggering chamber, and aconduit adapted to supply fluid under pressure thereto.

7. An impact ram according to claim 1 in which the conduitry comprises acharging port opening into the charging chamber for admitting fluidunder pressure thereto; and a valve adapted to connect the charging portto a source of pressure in one condition.

8. An impact ram having an axis, comprising: a body having an internal,axially-extending body cylinder; 21 plunger having an internal,axially-extending plunger cylinder; a piston axially slidahly fitted insaid plunger cylinder in fluid-sealing relationship therewith, the bodyand plunger, and the piston and plunger being relatively axiallyslidable; a laterally-extending collar on the body making afluid-sealing fit with the external surface of the plunger; alaterally-extending collar on the plunger mak ing a fluid sealing fitwith the body cylinder, whereby a return chamber of variable volume isdefined by the body cylinder, the plunger and the collars, the returnchamber being adapted to receive gas under pressure; a return surface onthe plunger collar facing into the return chamber; a triggering surfaceon the plunger collar facing toward a first, closed end of the bodywithin the body cylinder; a peripheral seal carried by the body at saidfirst end thereof inside the body cylinder; a peripheral seal carried bythe plunger at its end adjacent said seal on the body, the plungercylinder opening into said lastnarned seal, whereby the said two sealsare adapted to make a fluid-sealing closure when the plunger is moved toits full extent toward said first end, said closure separating atriggering chamber formed between the said first end and the triggeringsurface within the body cylinder from a charging chamber formed betweensaid first end and the piston inside the plunger cylinder, the Oppositeend of the plunger cylinder being closed, whereby the piston forms anaccumulator chamber of variable volume, said accumulator and chargingchambers being separated from each other by the piston; an accumulatorport opening through the plunger into the accumulator chamber foradmitting a residual charge of gas under pressure; accumulator chambervalve means for closing said accumulator port to retain the residualcharge therein; conduitry opening into the charging chamber; valve meanscontrolling flow of fluid in said conduitry; a triggering port openingthrough the body into the triggering chamber for admitting fluid underpressure thereto; and triggering chamber valve means controlling flow offluid through the triggering port, whereby pressure in the returnchamber moves the plunger to said full extent to cause said seals toseat, and pressure next introduced into the charging chamber moves thepiston and compresses the gas in the accumulator chamber, fluid underpressure next being admitted to the triggering chamber to move theplunger so as to separate the seals and exert pressure of the chargingchamber over the full lateral area of the plunger, thereby to cause theplunger body to move axially so as to increase the spacing between thefirst end of the body and the triggering surface.

9. An impact ram according to claim 8 in which the opening in theplunger adjacent said first end is tapered, narrowing toward said firstend, and in which the piston includes a reduced portion adapted to entersaid opening so as gradually to reduce the lateral separation betweenthem, thus decelerating the plungers motion away from the first end.

11?. In an impact ram which has an axis, a body with an internal,axially-extending body cylinder, a plunger axially slidable in said bodycylinder, which plunger forms with the body cylinder adjacent to a firstend of each a charging chamber adapted to receive a fluid underpressure, the improvement comprising: an internal, axially-extendingplunger cylinder in said plunger which opens at the first end of saidplunger and which is closed at the other end, and a piston making asliding fit in said plunger cylinder whereby to define an accumulatorchamber of variable volume in said plunger cylinder, the accumulatorchamber being adapted to contain a charge of gas under pressure, meansmovable with the piston forming a movable fluid-sealing interfacebetween the said gas and the fluid in the charging chamber, whereby withthe plunger and body in mutual axial restraint, a positive differentialpressure in the charging chamber will move the piston into theaccumulator chamber to reduge its volume and compress the gas therein,the compressed gas in the accumulator chamber supplying energy to thecharging chamber and thereby to the first end of the plunger when saidrestraint is released, so as to move the plunger axially relative to thebody while the piston moves in the plunger cylinder axially toward thesaid first end of the plunger.

11. Apparatus according to claim 10 in which the plunger cylinder opensonto the first end of the plunger through an opening, which openingincludes a restriction, and in which the piston has a nose of lesserlateral dimensions than those of the restriction whereby cooperativelyto regulate the axial velocity of the piston relative to the plungerover at least a portion of the axial traverse of the piston.

12. Apparatus according to claim 11 in which the restriction and noseinclude tapered portions.

13. Apparatus according to claim 11 in which the restriction and thenose include seats which seal with one another at the farthest excursionof the piston toward said first end.

14. Apparatus according to claim 10 in which the restriction includes aplurality of steps, and in which the piston nose includes a plurality ofsteps, whereby there is provided a plurality of pairs of mutuallycooperating segments to regulate the velocity of the piston asaforesaid.

15. Apparatus according to claim 14- in which the steps are spaced apartby axially-extending cylindrical se ments.

Reterences tCited UNITED STATES PATENTS 2,679,827 6/1954 Perdue 91-42,829,498 4/ 1958 Ferguson 60-545 3,103,136 9/1963 Bollar 60-523,105,414 10/1963 Cvjetkour et al. 9l-4l7 3,158,048 11/1964 Bollar 9283,200,715 8/1965 Ottcstad 91-392 3,202,059 8/1965 Ottestad et al 9l3923,205,790 9/1965 Bollar 72453 3,267,677 8/1966 Bollar 92134 EDGAR W.GEOGHEGAN, Primary Examiner. PAUL E. MASLOUSKY, Assistant Examiner.

